Society depends on the science of quantitative risk assessment for protection against environmental exposures that can cause cancer, impaired reproductive health and other adverse health effects. Due to limitations and availability of reliable epidemiological information, controlled experiments in laboratory animals continue to play an important role in the risk assessment process. the important and high cost of these studies warrant continued statistical research to ensure that the best design and analysis techniques are being used. This is a proposal to address a selection of statistical problems that arise in the design and analysis of rodent carcinogenicity as well as developmental and reproductive toxicity (teratology) experiments. the broad aims are: 1. To evaluate and extend existing methods for fitting three-state models for carcinogenicity data. 2. To extend and apply empirical Bayes methods to incorporate various types of historical control of methods to adjust for body weight in the analysis of tumor incidence data. 3. to study statistical models for multiple outcomes that arise in teratology studies. Empirical data analysis will play a central role in the proposed research.